1. Field of the Invention
The present invention relates to a folding cylinder and more specifically to a folding cylinder employed in a folder which introduces the webs laid one over another between the folding cylinder and a cutting cylinder which are disposed side by side and rotate in opposite directions to each other, cuts the webs in a section of the printed papers by cutting the webs by bringing the cutting knife in the cutting cylinder into engagement with the knife receiving member in the folding cylinder, and then folds the section of the printed papers. Still more specifically, the present invention relates to a folding cylinder employed in a folder capable of so-called collect run in which an inside section of the printed papers is held temporarily by the pins in the folding cylinder so that the inside section wraps around the circumference of the folding cylinder and waits for an outside section of the printed papers. The outside section of the printed papers is superposed on the inside section of the printed papers and cut after the folding cylinder is rotated by a full turn, and then the superposed sections are folded together.
2. Description of the Prior Art
So-called collect run, in which a folding cylinder and cutting cylinder are disposed side by side, an inside section of the printed papers is wrapped around the folding cylinder and made to wait for an outside section of the printed papers, and the inside section of the printed papers and the outside section of the printed papers are superposed and folded together, has been known. Such a prior art is disclosed, for example, in "Newspaper Leterpress Presses", ANPA Res. Inst., Third edition, First printing, pp. 20, 150-152, 154. A typical known so-called 3:2 folder in which a cutting cylinder turns by half a turn while a folding cylinder turns by one-third of a turn will be described hereunder with reference to FIG. 7 showing part of the folder and FIGS. 8(a) to 8(f) sequentially showing the operating processes in one-third of a turn of the folding cylinder.
In collecting an outside section 204A of the printed papers each having a printed surface A and an inside section 204B of the printed papers each having a printed surface B in layers and folding sections 204A and 204B together on this conventional folder, the different printed surfaces A and printed surfaces B are printed longitudinally alternately on each web 200, and each web is collected in layers before a former 2 to form the webs 201. The webs 201 are delivered to a former 2 by a drag roller 1 to fold the webs 201 by the former 2. Alternatively the webs 201 are slit longitudinally by a slitter 3 as they pass the drag roller 1, and then the separated parts of the webs are superposed one over the other as shown in FIG. 7.
Then, the webs 201 are delivered between a folding cylinder 4 and a cutting cylinder 5. In a collect run in which the outside section 204A of the printed papers each having a printed surface A is placed outside with respect to the folding cylinder 4, the inside section 204B of the printed papers each having a printed surface B is held by the pins 61 at a portion immediately behind a portion to be the leading end of the inside section 204B as shown in FIG. 8(a) and the inside section 204B is pressed against the folding cylinder 4 as the folding cylinder 4 and the cutting cylinder 5 rotate in opposite directions indicated by arrows in FIG. 8(a). The inside section 204B of the printed papers is pressed against the folding cylinder 4 by a paper pressing member 81 disposed so as to be brought into contact with a cutting knife receiving member 91 and protruded from the circumference of the cutting cylinder 5 on both sides of a cutting knife 71 by being urged by an elastic member, not shown, engaging the inner end thereof so that the outer end thereof is positioned practically flush with the cutting edge of the cutting knife 71.
When the paper pressing member 81 engages and presses the webs 201, the elastic member urging the paper pressing member 81 radially outward is compressed as the paper pressing member 81 is caused to retract, and then the cutting knife 71 engages the cutting knife receiving member 91 to cut off an end piece 203 (FIG. 8 (a)). At this time, the pins 62 are retracted inside the folding cylinder 4 to release the section of the printed paper, which action is similar to the action of the pins 63 in a state shown in FIG. 8(c) and that of the pins 61 in a state shown in FIG. 8(e).
On the other hand, as shown in FIG. 8(a), a folding blade 101 protrudes outside from the folding cylinder 4 in a state shown in FIG. 8(c) or in a state shown in FIG. 8(e) to insert the section of the printed paper released from the pins 62 (63, 61) between second fold rollers 11.
Then, as the folding cylinder 4 rotates, the webs 201 held by the pins 61 are introduced between the folding cylinder 4 and the cutting cylinder 5, while the same is wrapped around the circumference of the folding cylinder 4. Then, the webs 201 are held at a portion immediately behind a portion to be the leading end of the outside section 204A of the printed papers, each having a printed surface A with the pins 63 and are pressed against the folding cylinder 4 as the folding cylinder 4 and the cutting cylinder 5 rotate as shown in FIG. 8(b).
The section 204A is pressed against the folding cylinder 4 with a paper pressing member 82 disposed so as to come into contact with a cutting knife receiving member 93 and protruded from the circumference of the cutting cylinder 5 on both sides of a cutting knife 72 by being urged by an elastic member, not shown, engaging the inner end thereof so that the outer end thereof is positioned practically flush with the cutting edge of the cutting knife 72. The paper pressing member 82 retracts and compresses the elastic member when the same engages the webs 201, and thereby the cutting knife 72 engages the cutting knife receiving member 93 to cut the webs 201 along a line separating the trailing end of the inside section 204B of the printed papers each having a printed surface B and the leading end of the outside section 204A of the printed papers each having a printed surface A (FIG. 8(b)). On the other hand, the pins 61 do not retract inside the folding cylinder 4 and keep holding the section as the pins 62 in FIG. 8(d) and the pins 63 in FIG. 8(f), while the folding blade 102 remains retracted within the folding cylinder 4. Therefore, the section held by the pins 61 (62, 63) remains on the circumference of the folding cylinder 4 and rotates together with the folding cylinder 4.
Thereafter, the cutting cylinder 5 and other members perform the actions shown in FIGS. 8(c) and 8(d) sequentially at every one-third of a turn of the folding cylinder 4.
In this conventional folder, the cutting cylinder 5 turns by half a turn to cut the webs 201 at every one-third of a turn of the folding cylinder 4. A bracket 109 holding the folding blades 101 and 102 turns by one full turn within the folding cylinder 4 to protrude the folding blade 101 outside the folding cylinder 4 in order to fold the section of the printed paper while the folding cylinder 4 turns by two-thirds of a turn. The pins 61, 62 and 63 are retracted inside the folding cylinder 4 in synchronism with the protrusion of the folding blade 101 outside the folding cylinder 4 after the outside section 204A of the printed papers each having a printed surface A has been superposed on the inside section 204B of the printed papers each having a printed surface B.
Problems to be Solved by the Invention
In the collect run employing the above-mentioned well-known folding cylinder, a problem lies in the cutting operation shown in FIGS. 8(d) and 8(f) in which the section 204A is superposed on the section 204B which has previously been cut and separated from the webs 201 and is held on the circumference of the folding cylinder 4 and the trailing end of the section 204B and the leading end of the section 204A are formed simultaneously. This problem will be explained in detail with reference to FIGS. 9 and 10. FIG. 9 is an enlarged view corresponding to a portion indicated by X in FIG. 8(d) and FIG. 10 is a view similar to FIG. 9, in which a mode of tension of the webs 201 when the cutting cylinder 5 is removed tentatively is shown. In the cutting operation to form the trailing end of the section 204B, the webs 201 for forming the leading end of the section 204A mount the leading portion of the section 204B waiting on the circumference of the folding cylinder 4. Therefore, a portion of the webs 201 around the leading end corresponding to a cutting position is inclined, and gap 19' is formed between the webs 201 and the circumference of the folding cylinder 4 as shown in FIG. 10. When the cutting knife 72 engages the cutting knife receiving member 91 to cut the webs 201 in such a state, the paper pressing member 82 protruding on both sides of the cutting knife 72 is unable to press the webs 201 firmly with the entire area of the outer end face thereof, because the portion of the webs 201 lying over the cutting position is inclined. Furthermore, the cutting knife 72 is unable to cut the webs 201 along the normal. Consequently, when the cutting knife 72 engages the cutting knife receiving member 91, the papers of the section 204B, particularly the several papers from the top among the papers of the knife 204B lying beyond the cutting position and pressed unstably by the paper pressing member 82 are drawn backward by the cutting knife 72 so that the cutting knife 72 is aligned with the normal. The papers thus drawn backward move further backward following the movement of the cutting knife 72, and the webs 201 are cut while several papers are moving backward (FIG. 9). Consequently, the marginal portion W (FIG. 8(d)) beyond the pins of each of the papers drawn backward is torn by the pins 62 and those papers are not held by the pins 62 at the completion of the cutting operation. Accordingly, those papers which are not held by the pins 62 are unable to follow the rotation of the folding cylinder 4 and stay about the circumference of the folding cylinder 4 disturb the folder in its normal operation.